1. Field of the Invention
This invention relates to the field of data processing systems. More particularly, this invention relates to the verification of the secure operation of data processing systems.
2. Description of the Prior Art
It is known to provide data processing systems with both a secure domain of operation and a non-secure domain of operation. In the secure domain of operation the data processing system is able to access secure within a memory which is non-accessible when the data processing system is operating in the non-secure domain. The secure data may, for example, be bank data, cryptographic keys, personal information or the like. In order to enhance the security of operation of such devices it is useful to be able to demonstrate to the user that the device is operating in a secure mode.
It is known for a device to display an indication on a display screen to indicate that a secure mode of operation or communication is currently being used. As an example, browser software may display a symbol indicating that a secure web browsing session is taking place and the user can check for this indication before inputting secret information, such as a personal identification number (PIN), credit card details or the like.
A problem with this approach is that it is possible to fake the display of the symbol indicating that the system is operating securely, i.e. in a secure domain. A malicious programmer who is able to mislead a user into believing that their device is operating in the secure domain by displaying a fake version of the indication associated with the secure domain may then inappropriately gain access to secret information.